1. Field of the Invention
This invention relates to a bistable semi-conductor component and more particularly to one having at least three p-n junctions and which may be switched from a blocked state to a conducting state. One zone is called the base and is located between the second and third p-n junctions. Another zone is called the control zone and is located between the first and second p-n junctions. Such semi-conductor components are generally referred to as thyristors.
2. Description of the Prior Art
Known thyristors generally consist of four zones, comprised alternately of N and P type semiconductor material. When in the forward-conducting state, the inner zones, in particular the high-ohmic base, will be flooded with charge carriers. This flooding causes a delay in the blocking capacity of the thyristor in its backward blocking state as regards the renewed forward potential, because the excess charge carriers first must decay by recombining in the base (see for instance Koehl, Scientia Electrica, vol. XI, fasc. 1, 1965, p. 30-31). The charge carrier density in the flooded state being some 10 orders of magnitude over the carrier density in the equilibrium state, it is assumed that on the average approximately four-fold to ten-fold of the average carrier life is required for complete decay of carrier excess by recombination. This time which is required for carrier decay is called the release time.
However, the reduction of carrier life in order to reduce the release time is limited to the extent that below a critical lifetime for a given base width, the drop in transmission potential will increase exponentially. While one may thus improve the dynamic blocking behavior of the thyristor by decreasing the carrier life, and thus improve the release time, a degradation of the conducting behavior below a certain limit must be simultaneously expected.